Conventionally, an anti-counterfeiting additive called “taggant” (or “taggent”) has been used to prevent articles such as valuable papers from counterfeiting. The taggant is required to be inexpensive and highly difficult to be counterfeited. It is also required that the authenticity can be assessed easily and quickly.
Such taggant particles are disclosed as patterned markers that are made to be recognizable under optical magnifying apparatus. These markers are formed either by a lithography method, which is in the technical field of integrated circuits, or by other methods, which are in the technical field of micro machining. The markers are formed so that they can be recognized with information based on the designs such as shapes, logos, personal signatures, dates, and words. The markers can be fixed by adhering and drying liquid adhesive, which is mixed uniformly with these markers, onto a surface of a document and the like (See Patent Document 1).